If I understand your question correctly then, yes, you can use your party members (NPC) for breaking down components and making items for cheaper, but only on workbenches and labstations present on the planets, not on the Ebon Hawk. I'm pretty sure only your PC can use the tables on the Ebon Hawk.

Yes and no. Number of components you get for breaking down items is dependent upon your PC's repair skill (and you don't get any additional components past 20 skill points).

However, item creation is dependent upon the person using the bench. So while it doesn't matter which party member is breaking items into components, it does matter which party member is using components to make items.